Outlook 2010 Will Use Word 2010 HTML Rendering Engine

I don’t think any software is perfect. Certainly Microsoft Outlook has been criticized over the years for its flaws—security flaws many years ago, poor IMAP performance, flaky PST issues, and performance degradation. A recent wave of complaints focuses on the HTML rendering engine for creating and reading HTML email messages. Through email marketing companies and sites like fixoutlook.org, this discussion has been renewed since it became clear that Office Outlook 2010 will maintain its Word counterpart as the HTML renderer. (This has been known for some time, but perhaps opponents to Word rendering held out hope that Outlook would return to using Internet Explorer (IE) to render HTML content.)

Maybe your company produces HTML newsletters or your marketing department has expressed some concern that some HTML emails they send or receive may not be presented in the manner intended, especially those using Cascading Style Sheets (CSS). Outlook 2000, 2002, and 2003 all used Internet Explorer to render HTML content within an Outlook window. Outlook 2007 introduced Word 2007 to render HTML. Word does not offer the same HTML experience that Internet Explorer would provide, and many CSS properties are not recognized when rendered by Word. For some background and a full description of HTML and CSS rendering in Word 2007 see http://msdn.microsoft.com/en-us/library/aa338201.aspx.

After using Outlook 2007 for almost 3 years, I don’t remember ever receiving an HTML message that didn’t render sufficiently within Outlook, other than spam. If you do receive an email using extensive CSS that is not readable within Outlook 2007, you can open the message with IE. To view an email message rendered in IE, open the message in Outlook 2007, select Other Actions in the Office ribbon, and then Open In Browser, as shown in Figure 1 below. By default, you will receive a security warning about opening suspect HTML in IE, as shown in Figure 2 below. Click OK to launch IE. To render the email message in the browser, Outlook saves the message to the \Temporary Internet Files\content.outlook\ folder as MIME HTML with an .mht extension, and then launches IE pointing to the saved .mht file.